Interaction of fast (keV) hydrogen ions/atoms with surfaces : diffraction and negative ion formation

In this thesis, we have investigated experimentally the scattering of hydrogen atoms and ions on solid surfaces at grazing incidence. The projectile energy ranges from several hundred eV to few keV. The formation of H- ions is studied on highly oriented pyrolytic graphite (HOPG) surface; and surface diffraction is carried out on LiF(001) surface with H° and H+ particle scattering. Both experiments were performed in the same experimental setup (see Figure 1.2 and 2.1)—with grazing scattering geometry and a PSD (position sensitive detector) located downstream to record scattered particles. For charge state analysis a set of electrostatic plates is inserted between sample and PSD. During the experiment, coincident measurement technique is used to identify the energy loss associated to 0, 1, 2…electrons emission. Clear evidence of diffraction with inelastic scattering by proton on LiF(001) has been obtained, which has not been observed before. Indeed, the group of H. Winter reported that no diffraction exists with inelastic scattering of H° on LiF(001). However, according to our result, a coherence scattering factor still exists even though the electron capture by the proton is an inelastic process. For negative ion formation on HOPG surface, we report here the highest fraction of H- (~10%) measured in grazing scattering experiments; it is larger than those obtained on ionic insulators, the latter being typically 10 times larger than those measured on clean metals. These results confirm the high yields of negative hydrogen ions from graphite reported in the literature. Electron emission and energy loss of scattered beam have also been deciphered via coincidence measurement. Due to the special structure of HOPG, two kinds of electron emissions (σ and π-band electron) and energy losses (cycles and metal-like energy loss) have been measured. Furthermore, the total electron emission on HOPG with insulator-like behavior and total energy loss with metal-like are the most representative property of HOPG which have been first presented in this thesis.

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Source https://theses.hal.science/tel-00863479
Author Xiang, Yang
Maintainer CCSD
Last Updated May 9, 2026, 16:49 (UTC)
Created May 9, 2026, 16:49 (UTC)
Identifier NNT: 2012PA112161
Language en
Rights https://about.hal.science/hal-authorisation-v1/
contributor Institut des Sciences Moléculaires d'Orsay (ISMO) ; Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)
creator Xiang, Yang
date 2012-09-14T00:00:00
harvest_object_id d3e1f556-d3cc-483a-885c-eb3308b2f390
harvest_source_id 3374d638-d20b-4672-ba96-a23232d55657
harvest_source_title test moissonnage SELUNE
metadata_modified 2026-03-30T00:00:00
set_spec type:THESE